An internal combustion engine of the stated type is used as a motor vehicle drive unit. Within the context of the present disclosure, the expression “internal combustion engine” may encompass Otto-cycle engines and also hybrid internal combustion engines, which utilize a hybrid combustion process with applied ignition, and hybrid drives which comprise not only an applied-ignition internal combustion engine but also an electric machine which can be connected in terms of drive to the internal combustion engine and which receives power from the internal combustion engine or which, as a switchable auxiliary drive, additionally outputs power.
Internal combustion engines may comprise a cylinder block and at least one cylinder head which are connected to one another to form the cylinders and the combustion chambers thereof. The cylinder block, as the upper crankcase half, generally serves for the mounting of the crankshaft and for accommodating the piston and the cylinder sleeve of each cylinder.
The crankshaft which is mounted in the crankcase absorbs the connecting rod forces and transforms the oscillating stroke movement of the pistons into a rotational movement of the crankshaft. The upper crankcase half formed by the cylinder block is generally supplemented by the oil pan, which can be mounted on the cylinder block and which serves as the lower crankcase half.
The cylinder head may accommodate the valve drives used for the charge exchange. During the course of the charge exchange, the discharge of the combustion gases via the exhaust-gas discharge system takes place via the outlet openings, and the feed of the charge air via the intake system takes place via the inlet openings of the at least two cylinders.
Each lifting valve moves, so as to realize, that is to say perform, a maximum valve lift, between an open position and a closed position, and in so doing opens up the valve-specific opening for a certain opening duration during the opening process. The valve actuating mechanism desired for the movement of a valve, including the valve itself, is referred to as the valve drive.
The valve drive may open and close and/or shut-off the inlet opening and outlet opening at the correct times, with a fast opening of the largest possible flow cross sections to maintain the throttling losses in the inflowing and outflowing gases low in order to ensure improved charging of the cylinders and an effective discharge of the exhaust gases. Accordingly, the cylinders may be provided with two or more inlet and outlet openings.
The at least two cylinders of the internal combustion engine to which the present disclosure relates are equipped with at least one inlet opening and at least two outlet openings.
According to the previous examples, the intake lines which lead to the inlet openings, and the exhaust lines which adjoin the outlet openings, are at least partially integrated in the cylinder head. The exhaust lines of the cylinders may be merged to form one common overall exhaust line, or else, as in the internal combustion engine according to the disclosure, in groups to form two overall exhaust lines. The merging of exhaust lines to form an overall exhaust line is referred to as an exhaust manifold, wherein, within the context of the present disclosure, the overall exhaust line is regarded as belonging to the exhaust manifold.
Downstream of the manifolds, the exhaust gases may be supplied, for the purposes of supercharging, to the turbine of at least one exhaust-gas turbocharger, and/or to one or more exhaust-gas aftertreatment systems. In some cases, exhaust gas is recirculated into the intake system.
In the case of the internal combustion engine to which the present disclosure relates, exhaust gas originating from the cylinders is supplied, for supercharging purposes, via a first overall exhaust line to the turbine of at least one exhaust-gas turbocharger, and is subjected to exhaust-gas aftertreatment downstream of the turbine. A second overall exhaust line may connect the cylinders at the outlet side to the intake system upstream of the compressor of the at least one exhaust-gas turbocharger. Here, the exhaust lines of the cylinders are configured so as to form two groups, each group comprising at least one exhaust line from each cylinder, and the exhaust lines of each group merging, in each case with the formation of an exhaust manifold, to form an overall exhaust line.
Internal combustion engines of this type, and methods for operating such internal combustion engines, are described for example in the German laid-open specification DE 10 2016 111 686 A1. In one variant of DE 10 2016 111 686 A1, it is for example possible for the exhaust gas of a first group to be introduced into the intake system downstream or upstream of a compressor of an exhaust-gas turbocharger and/or fed to a turbine of the exhaust-gas turbocharger, whereas the exhaust gas of a second group can be introduced upstream of the compressor and/or fed to the turbine. It is sought to achieve improved knocking control and improved scavenging or purging of the cylinders with fresh air, while at the same time, when desired, maintaining a stoichiometric air ratio during the exhaust-gas aftertreatment. The latter may relate to exhaust-gas aftertreatment (e.g., three-way catalytic converters). An acceleration of the exhaust-gas turbocharger can likewise be realized via an increase of the gas throughput through the cylinders.
The advantage of an exhaust-gas turbocharger in relation to a supercharger, which is driven via an auxiliary drive, consists in that an exhaust-gas turbocharger utilizes the exhaust-gas energy of the hot exhaust gases, whereas a supercharger draws the energy needed for driving it directly or indirectly from the internal combustion engine and thus adversely affects, that is to say reduces, the efficiency, at least for as long as the drive energy does not originate from an energy recovery source. If the supercharger is not one that can be driven via an electric machine, that is to say electrically, a mechanical or kinematic connection for power transmission may be arranged between the supercharger and the internal combustion engine, which also adversely affects or determines the packaging in the engine bay.
An exhaust-gas turbocharger comprises a compressor and a turbine which are arranged on the same shaft. The hot exhaust-gas flow may be fed to the turbine and expands in the turbine with a release of energy, as a result of which the shaft is set in rotation. The energy released by the exhaust-gas flow to the turbine and ultimately to the shaft is used for driving the compressor which is likewise arranged on the shaft. The compressor delivers and compresses the charge air supplied to it, as a result of which supercharging of the at least two cylinders is obtained. A charge-air cooling arrangement may be provided to cool the compressed charge air before it enters the cylinders.
Supercharging may increase the power of the internal combustion engine. Here, the air used for the combustion process is compressed, as a result of which a greater air mass can be supplied to each cylinder per working cycle. In this way, the fuel mass and therefore the mean pressure can be increased. Supercharging may increase the power of an internal combustion engine while maintaining an unchanged swept volume, or for reducing the swept volume while maintaining the same power. In all cases, supercharging leads to an increase in volumetric power output and a more expedient power-to-weight ratio. If the swept volume is reduced, it is possible, given the same vehicle boundary conditions, to shift the load collective toward higher loads, at which the specific fuel consumption is lower.
Supercharging consequently assists in the efforts to minimize fuel consumption of an internal combustion engine, that is to say to improve the efficiency of the internal combustion engine.
A suitable transmission configuration may provide downspeeding, whereby a lower specific fuel consumption is likewise achieved. In the case of downspeeding, use is made of the fact that the specific fuel consumption at low engine speeds is generally lower, in particular in the presence of relatively high loads.
With targeted configuration of the supercharging, it is also possible to obtain advantages with regard to the exhaust-gas emissions. With suitable supercharging for example of a diesel engine, the nitrogen oxide emissions can therefore be reduced without any losses in efficiency. At the same time, the hydrocarbon emissions can be positively influenced. The emissions of carbon dioxide, which correlate directly with fuel consumption, decrease in any case with falling fuel consumption.
To be able to adhere to limit values for pollutant emissions in future, further measures in addition to supercharging are necessary, for which reason use is generally made of various exhaust-gas aftertreatment systems for converting the pollutants.
The internal combustion engine to which the present disclosure relates is equipped not only with the supercharging arrangement but also with an exhaust-gas aftertreatment arrangement.
It may be desired to arrange the turbine of an exhaust-gas turbocharger as close as possible to the outlet openings of the cylinders to increasingly utilize the exhaust-gas enthalpy of the hot exhaust gases, which is determined significantly by the exhaust-gas pressure and the exhaust-gas temperature, and to allow a fast response behavior of the turbine and thus of the turbocharger. Furthermore, the close-coupling may minimize the thermal inertia and the volume of the line system between the outlet openings of the cylinders and of the turbine, which may be achieved by reducing the mass and the length of the exhaust lines. Here, the integration of the exhaust manifolds into the cylinder head is expedient in achieving this aim.
The various exhaust-gas aftertreatment systems may desire certain minimum temperatures in order to be able to convert the respective pollutants, for which reason exhaust-gas aftertreatment systems should also be positioned in as close-coupled a position as possible. With regard to the arrangement of a turbine and of an exhaust-gas aftertreatment system, there is thus a conflict of aims, wherein the turbine may be given the higher priority, as is the case in the internal combustion engine of the present disclosure.
The conversion of the pollutants during the course of the exhaust-gas aftertreatment may be less than a threshold during a cold-start, owing to the relatively great distances that the exhaust gases covers from the exhaust valve outlet openings to the exhaust-gas aftertreatment systems, wherein the turbine functions, and is to be regarded, as an additional temperature sink.
The inventors recognize the above described issues and have come up with a way to at least partially solve them. In one example, a supercharged internal combustion engine having three cylinders in an in-line arrangement, in which internal combustion engine each cylinder has at least one inlet opening for the feed of charge air via an intake system and at least two outlet openings for the discharge of exhaust gas via an exhaust-gas discharge system, each outlet opening being adjoined by an exhaust line, at least one exhaust-gas turbocharger is provided which comprises a turbine arranged in the exhaust-gas discharge system and a compressor arranged in the intake system, the exhaust lines are configured so as to form two groups, each group comprising at least one exhaust line from each cylinder, and the exhaust lines of each group merging, in each case with the formation of an exhaust manifold, to form an overall exhaust line, the first overall exhaust line of a first group opens into the turbine of the at least one exhaust-gas turbocharger, the second overall exhaust line of a second group opens into the intake system upstream of the compressor of the at least one exhaust-gas turbocharger, and at least one exhaust-gas aftertreatment system is provided in the exhaust-gas discharge system downstream of the turbine of the at least one exhaust-gas turbocharger, and which internal combustion engine is distinguished by the fact that a discharge of exhaust gas via the first overall exhaust line can be prevented, and a blow-off line is provided in which a shut-off element is arranged and which branches off, with the formation of a first junction, from the exhaust manifold of the second group and which opens, with the formation of a second junction, into the exhaust-gas discharge system downstream of the turbine of the at least one exhaust-gas turbocharger, an accumulator for unburned hydrocarbons being provided in the blow-off line.
In the case of the internal combustion engine according to the disclosure, exhaust gas originating from the exhaust manifold of the second group can be conducted, via the blow-off line, past the turbine of the exhaust-gas turbocharger. An accumulator for unburned hydrocarbons is provided in the blow-off line.
In one example, during the warm-up phase, in particular during a cold start, for the exhaust gas to be treated in a close-coupled position and in accordance with demand, wherein unburned hydrocarbons situated in the exhaust gas are collected and stored in the accumulator provided according to the disclosure.
For this purpose, the discharge of exhaust gas via the first overall exhaust line is prevented, that is to say suppressed via a shut-off element in the exhaust-gas discharge system upstream or downstream of the turbine. Alternatively, the discharge of exhaust gas via the first overall exhaust line can be prevented by equipping the outlet openings of the first group with switchable valves, and deactivating the valves. The introduction of exhaust gas into the intake system may be stopped, for example by closing a shut-off element provided in the second overall exhaust line.
By opening the shut-off element provided in the blow-off line, the blow-off line is opened up for the exhaust gas originating from the second exhaust manifold, and the accumulator for unburned hydrocarbons is charged with exhaust gas.
The unburned hydrocarbons collected in the accumulator can then be released again, and oxidized, under other operating conditions. The unburned hydrocarbons collected in the accumulator are preferably introduced into the exhaust-gas discharge system with the exhaust gas flowing through the blow-off line, and oxidized using a catalytic converter in the exhaust-gas discharge system.
Since no exhaust gas is discharged from the cylinders via the first overall exhaust line during the warm-up phase, the outlet valves belonging to the outlet openings of the second group may be actuated with regard to an effective charge exchange. That is to say, the outlet openings of the second group may be opened such that the maximum valve lift Δhmax is realized in each case in a compression phase of the associated cylinder.
When the internal combustion engine has warmed up, when the exhaust gas is discharged from the cylinders predominantly via the first overall exhaust line, the outlet valves of the second group can also, as desired, be opened such that the maximum valve lift Δhmax is realized in each case upon the transition from the compression phase into an expansion phase of the associated cylinder; in some cases at the charge exchange top dead center.
By doing this, emissions from the internal combustion engine may decrease.
According to the previous examples, the exhaust lines of three-cylinder in-line engines are seldom grouped, because three-cylinder in-line engines may be poorly suited to grouping, in particular cylinder grouping. The merging of the exhaust lines according to the disclosure however avoids these issues.
The internal combustion engine according to an example has exactly three cylinders in an in-line arrangement. The internal combustion engine according to the disclosure is thus a three-cylinder in-line engine.
Embodiments of the supercharged internal combustion engine may further comprise where each cylinder has at least two inlet openings for the supply of charge air via the intake system.
Through the provision of large flow cross sections, the throttling losses in the inflowing charge air can be kept low, and desired charging of the cylinders can be maintained. It may therefore be desired for the cylinders to be equipped with more than one inlet opening, that is to say with at least two inlet openings.
Based on similar or analogous considerations, embodiments of the supercharged internal combustion engine may further comprise where each cylinder has three outlet openings for discharging exhaust gas via the exhaust-gas discharge system, the exhaust lines from two outlet openings per cylinder jointly forming the exhaust manifold of the first group. This may allow an effective discharge of the exhaust gas during the course of the charge exchange.
During normal operation of the warmed-up internal combustion engine (e.g., outside of a cold-start), the cylinders are evacuated primarily via the outlet openings or the exhaust lines of the first group. That is to say, the predominant exhaust-gas fraction is discharged from the cylinders via the first overall exhaust line via the first group of exhaust valves.
The exhaust lines of two outlet openings per cylinder may jointly form the exhaust manifold of the first group, that is to say open into the first overall exhaust line. Then, specifically, a larger inlet cross section, specifically two outlet openings, is provided for the exhaust-gas path via the first overall exhaust line.
For the reasons stated above, embodiments of the supercharged internal combustion engine are also advantageous in which the outlet openings belonging to the exhaust lines of the first group have a larger diameter than the outlet openings belonging to the exhaust lines of the second group.
This embodiment of the outlet openings assigns the or a larger inlet cross section to the exhaust-gas path via the first overall exhaust line, with a larger diameter of the outlet opening.
Embodiments of the supercharged internal combustion engine may comprise where the blow-off line opens, with the formation of the second junction, into the exhaust-gas discharge system upstream of an exhaust-gas aftertreatment system provided in the exhaust-gas discharge system.
If the blow-off line is opened with exhaust gas flowing therethrough, unburned hydrocarbons collected in the accumulator can be released again. The released unburned hydrocarbons pass together with the exhaust gas into the exhaust-gas discharge system at the second junction, and can in the present case be converted or oxidized in the exhaust-gas aftertreatment system provided downstream of the second junction. This is desired if the exhaust-gas aftertreatment system used is a three-way catalytic converter.
Nevertheless, the blow-off line may also open, with the formation of the second junction, into the exhaust-gas discharge system downstream of an exhaust-gas aftertreatment system provided in the exhaust-gas discharge system or else between two exhaust-gas aftertreatment systems, wherein the two exhaust-gas aftertreatment systems may also be exhaust-gas aftertreatment systems of the same type, for example two three-way catalytic converters.
Embodiments of the supercharged internal combustion engine may comprises where a shut-off element is provided in the exhaust-gas discharge system between the turbine of the at least one exhaust-gas turbocharger and the second junction for preventing the discharge of exhaust gas via the first overall exhaust line.
Embodiments of the supercharged internal combustion engine may further comprise where a shut-off element is provided in the exhaust-gas discharge system upstream of the turbine of the at least one exhaust-gas turbocharger for preventing the discharge of exhaust gas via the first overall exhaust line.
The above embodiments may use a shut-off element for adjusting the discharge of exhaust gas via the first overall exhaust line, wherein the shut-off element can be provided, or is to be provided, in the exhaust-gas discharge system upstream of the turbine or between the turbine and the second junction.
Embodiments of the supercharged internal combustion engine may comprise where the outlet openings belonging to the exhaust lines of the first group are each equipped with an at least partially variably actuatable outlet valve, which outlet valves can be deactivated for the purposes of shutting off the associated outlet opening and prevent the discharge of exhaust gas via the first overall exhaust line.
Embodiments of the supercharged internal combustion engine may comprise where a shut-off element is provided in the second overall exhaust line downstream of the first junction.
The introduction of exhaust gas into the intake system may be stopped by closing a shut-off element provided in the second overall exhaust line, when exhaust gas originating from the cylinders is discharged via the blow-off line and the discharge of exhaust gas via the first overall exhaust line is prevented, that is to say stopped.
The shut-off element provided in the second overall exhaust line may adjust the recirculation rate of an exhaust-gas recirculation arrangement.
Embodiments of the supercharged internal combustion engine may comprise where a cooler is provided in the second overall exhaust line downstream of the first junction.
The second overall exhaust line may be used for the recirculation of combustion gases from the outlet side to the inlet side, that is to say in the context of exhaust-gas recirculation, for the purposes of reducing nitrogen oxide emissions. To obtain a considerable reduction in nitrogen oxide emissions, high exhaust-gas recirculation rates may be desired, which may be of the order of magnitude of xEGR≈60% to 70% or more. Such high recirculation rates may desire cooling of the exhaust gas for recirculation, where the temperature of the exhaust gas is reduced and the density of the exhaust gas increased, so that a greater mass of exhaust gas can be recirculated. Consequently, an exhaust-gas recirculation arrangement may be equipped with a cooler. During the cooling process, condensate can form, which is precipitated in the cooler.
Embodiments of the supercharged internal combustion engine may comprise where a charge-air cooler is provided in the intake system downstream of the compressor of the at least one exhaust-gas turbocharger, where the charge-air cooler may cool the compressed charge air before it enters the at least two cylinders. The cooler lowers the temperature and thereby increases the density of the charge air, such that the cooler also contributes to improved charging of the cylinders, that is to say to a greater air mass. In effect, compression by cooling occurs.
Embodiments of the supercharged internal combustion engine may comprise where at least one three-way catalytic converter is provided, for the purposes of exhaust-gas aftertreatment, in the exhaust-gas discharge system downstream of the turbine of the at least one exhaust-gas turbocharger.
To reduce the pollutant emissions, internal combustion engines may be equipped with various exhaust-gas aftertreatment systems. Even without additional measures, oxidation of the unburned hydrocarbons (HC) and of carbon monoxide (CO) duly takes place during the expansion and discharge of the cylinder charge at a sufficiently high temperature level and in the presence of sufficiently large oxygen quantities. However, on account of the exhaust-gas temperature which falls quickly in the downstream direction, and the consequently rapidly decreasing rate of reaction, the reactions may be quickly halted.
For these reasons, use is made of catalytic reactors which, through the use of catalytic materials which increase the rate of certain reactions, allow an oxidation of HC and CO even at low temperatures. If nitrogen oxides are additionally to be reduced, this can be achieved by the use of a three-way catalytic converter, which however for this purpose utilizes stoichiometric operation (λ≈1) of the internal combustion engine within narrow limits. Here, the nitrogen oxides are reduced via the non-oxidized exhaust-gas components which are present, specifically the carbon monoxides and the unburned hydrocarbons, wherein the exhaust-gas components may be oxidized at the same time.
In internal combustion engines which are operated with an excess of air, the nitrogen oxides contained in the exhaust gas may not be reduced without introduction of a reducing agent in the exhaust gas. For the oxidation, oxidation catalytic converters are then provided in the exhaust-gas discharge system.
Embodiments of the supercharged internal combustion engine may comprise where the second exhaust valves corresponding to the second overall exhaust line are each equipped with an at least partially variably actuatable outlet valve, the outlet valve oscillating between an open position and a closed position, so as to realize a maximum valve lift Δhmax, and in the process opening up the associated outlet opening for the opening duration Δtmax during an opening process, and the opening process being capable of being advanced and/or retarded.
During some operations of the warmed-up internal combustion engine outside of a cold-start, when the valves of all of the cylinder openings are active and actuated, the actuation of the second outlet valves may be performed with the aim of recirculating exhaust gas or gas into the intake system upstream of the compressor. Additionally or alternatively, the second outlet valves may be actuated in response to a loading of an accumulator arranged in a blow-off line branching from the second overall exhaust line.
By contrast, during the warm-up phase and/or the cold-start, when no exhaust gas is discharged from the cylinders via the exhaust-gas discharge system via the first overall exhaust line, the outlet valves of the second group are correspondingly actuated, for an effective charge exchange. That is to say, the second exhaust valves may open at a time similar to an opening of the first exhaust valves outside of a cold-start. For this purpose, it may be possible for the opening process of the second exhaust valves to be advanced during the cold-start and/or warm-up phase. That is to say, the outlet openings of the second group are opened earlier, specifically such that the maximum valve lift Δhmax is realized in each case in the compression phase of the charge exchange of the associated cylinder.
When the warm-up phase and/or cold-start is complete, the opening process of the second exhaust valves may be retarded and the first exhaust valves may be activated. The maximum valve lift Δhmax is then realized in each case in the expansion phase of the charge exchange of the associated cylinder, or upon the transition from the compression phase into the expansion phase, possibly at the charge exchange top dead center. In other words, the second exhaust valves may open at a transition between an exhaust stroke and an intake stroke of a piston.
Embodiments of the supercharged internal combustion engine may comprise where the turbine of the at least one exhaust-gas turbocharger is in the form of a wastegate turbine, a bypass line branching off from the exhaust-gas discharge system upstream of the turbine and a shut-off element being provided in the bypass line.
Embodiments of the supercharged internal combustion engine may comprise where the turbine of the at least one exhaust-gas turbocharger has a variable turbine geometry, which permits extensive adaptation to the respective operating point by adjusting the turbine geometry or of the effective turbine cross section. Here, guide blades for influencing the flow direction may be arranged upstream of the impeller of the turbine. In contrast to the impeller blades of the rotating impeller, the guide blades do not rotate with the shaft of the turbine, that is to say with the impeller. The guide blades are arranged so as to be stationary but not so as to be completely immovable, rather so as to be rotatable about their axis such that the flow approaching the impeller blades can be influenced. In contrast, if the turbine has a fixed, invariable geometry, the guide blades are not only stationary but are also completely immovable, that is to say rigidly fixed, if a guide device is provided at all.
Embodiments of the supercharged internal combustion engine may comprise where the exhaust lines of the at least two cylinders merge to form the two overall exhaust lines within a cylinder head.
The cylinder head of a supercharged internal combustion engine is basically a component that is subject to high thermal and mechanical loading. In particular, with the integration of the exhaust manifolds, the thermal loading of the internal combustion engine and of the cylinder head is increased yet further, such that increased demands are to be placed on the cooling arrangement. Embodiments of the supercharged internal combustion engine may desired where a liquid-type cooling arrangement is provided.
A method for operating a supercharged internal combustion engine of a type described above, is achieved via a method comprising during the warm-up phase after a start of the internal combustion engine the discharge of exhaust gas via the first overall exhaust line is prevented, and exhaust gas originating from the second exhaust manifold is introduced via the blow-off line into the exhaust-gas discharge system downstream of the turbine of the at least one exhaust-gas turbocharger, unburned hydrocarbons situated in the exhaust gas being collected and stored in the accumulator.
For the operation of a supercharged internal combustion engine in which a shut-off element is provided in the second overall exhaust line downstream of the first junction, method variants may comprise where the shut-off element is held closed during the warm-up phase to decrease exhaust-gas recirculation flow. The shut-off element provided in the second overall exhaust line may however basically also serve, during the warm-up phase, for the setting of the exhaust-gas quantity recirculated into the intake system.
Method variants may further include where once the internal combustion engine has warmed up, the blow-off line is opened up for the purposes of oxidizing the unburned hydrocarbons collected in the accumulator.
In this context, method variants may comprise where the unburned hydrocarbons collected in the accumulator are released and introduced with exhaust gas into the exhaust-gas discharge system, the unburned hydrocarbons being oxidized using a three-way catalytic converter. As described above, by opening the second exhaust valves during the charge-exchange outside of the cold-start, a sufficient amount of air and exhaust gas may flow through the accumulator to the three-way catalytic converter to oxidize the unburned hydrocarbons.
For the operation of a supercharged internal combustion engine in which the outlet openings belonging to the exhaust lines of the second group are each equipped with an at least partially variably actuatable outlet valve, the outlet valve oscillating between an open position and a closed position, so as to realize a maximum valve lift Δhmax, and in the process opening up the associated outlet opening for the opening duration Δtmax during an opening process, and the opening process being capable of being advanced and/or retarded, method variants may comprise where, during the warm-up phase, the outlet valves belonging to the outlet openings of the second group are opened such that the maximum valve lift Δhmax is realized in each case in a compression phase of the associated cylinder.
In this context, method variants may comprise when the internal combustion engine has warmed up, the outlet valves belonging to the outlet openings of the second group are opened such that the maximum valve lift Δhmax is realized in each case upon the transition from the compression phase into an expansion phase of the associated cylinder.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.